A shading device of such type is disclosed in DE 1 10 2012 019 903 A1. The shading device is provided for a side window pane of a passenger vehicle and includes a flexible shading structure in the form of a roller blind fabric. The shading structure in a lowered rest position is adapted to be received in a roller blind cartridge which is attached fixed to the vehicle below a bottom edge of a window frame of the side window pane. The shading structure is capable of being deployed to a shading position. In the roller blind cartridge the shading structure is held on a roller blind shaft to be wound up and wound off, which shaft is rotatably mounted within the roller blind cartridge. An end face region of the shading structure that is in front in the direction of deployment is held tensioned between two lateral entrainers which are disposed fixed to the vehicle at the side of the window frame in guiding rails fixed to the vehicle. For displacing the entrainers, drive transmission means in the form of flexshafts are mounted in the guiding rails and driven by a drive unit. The shading structure is deployed from a door paneling of the side door upwards through a passage slot in the vicinity of a top of the roller blind cartridge. Said passage slot is capable of being closed by a pivotably mounted closing lid. Using a spring device, force in the opening direction is permanently applied to the closing lid. A control mechanism is provided to maintain the closing lid closed, as long as the shading structure is arranged in its rest position within the roller blind cartridge. Also, the control mechanism performs opening of the closing lid in response to a displacement movement of the entrainer along the lateral guiding rails starting from the rest position of the shading structure. The control mechanism also controls return of the closing lid back to its closed position, when the shading structure is transferred back to the rest position starting from its shading position. The control mechanism includes an entrainer slide engaging the closing lid via a second spring device. Upon displacement of the flexshafts, at least one entrainer entrains the entrainer slide which acts on the closing lid via the second spring device.